The conventional liquid crystal display (LCD) device is unable to have a very thin thickness (e.g., if each of two glass layers of the LCD has a thickness of 0.7 mm and two substrates thereof has a total thickness of 0.5 mm, then the thickness of the display screen of the LCD may be not smaller than 2 mm) and a very light weight due to the limitation on its structure. In contrast, the electronic ink display device has a very simple hardware structure and may have a thickness down to 1 mm. Furthermore, the electronic ink display device has a display screen thickness smaller than a half of the LCD and has a quite light weight, but has durability stronger than the common LCDs. The electronic ink has a wide range of applications, and especially the electronic ink may not only be applied to a glass surface but also be applied to a plastic surface, and thus an electronic ink display screen will not be as fragile as the LCD display screen. Meanwhile, the electronic ink display screen has very low power consumption, and may display a picture even in the case of a transient power lost. Its very low power consumption lies in that it has a very high reflectivity and contrast and thus there is no need to adopt a backlight to improve its readability.
Since a display device to which the electronic ink technology is applied has a same visual characteristic as a paper medium, and has the advantages of low power consumption, a thin thickness and a light weight etc., the display device may become a new favorite portable device. The display device is especially applicable to the scenarios which require a better display effect under various light rays, and this is unable to be achieved by a transmissive LCD or a reflective LCD.
The existing electronic ink display device may continue to use a manufacturing machine for the active matrix liquid crystal display (AMLCD) and have a simpler manufacturing process. Simply, an indium tin oxide (ITO) plastic substrate is coated with the electronic ink, and then attached to a TFT substrate through a laminator process. This process is the same as the polarizer film attaching process during the manufacturing process of the LCD, and may use an existing machine or the like to perform manufacturing. The simplification of the manufacturing process means an improved rate of finished products and an improved throughput, and furthermore a reduction in the thickness of a substrate reduces the cost.
The existing electronic paper typically adopts technologies such as the cholesterin liquid crystal display, the electrophoretic display (EPD) and the electrowetting display, among which the electrophoretic display is the most promising technology in this field. The electronic ink is mostly used in the electrophoretic display, and is unable to perform colorful display but only black and white display.
FIG. 1 shows a bi-stability reflective display, which adopts the electrophoresis (EP) phenomenon to achieve the display and contrast effect. Charged particles move to an electrode having an opposite polarity under the action of an electric filed, which is called EP. When the EP in an EP display occurs, an EP speed mainly depends on factors such as a viscosity of the EP liquid, a charge quantity of a particle (permanently charged or inductively charged), a dielectric property of an electrolyte, a magnitude of an applied electric field and a distance between electrodes. The EP speed may have an effect on a responding speed.
The film layer structure of the existing EPD as shown in FIG. 2 from top to bottom includes: a protective film 5, an organic plastic 6, an ITO 7, a bonding glue layer 8, an adhesion layer 9, and a pixel electrode (not shown). Microcapsules 1 are provided (between two layers of electrodes) in the bonding glue layer 8. The microcapsules 1 may include positively charged white particles 2 which are generally TiO2 particles, negatively charged black particles 3, and a transparent EP liquid 4. The distribution of the white particles and black particles on the electrodes may be controlled by controlling the direction of the electric field. For example, when a black picture is displayed, a positive voltage is applied on an upper electrode and a negative voltage is applied on a lower electrode. Under the action of the electric field, the positively charged white particles move downward and close to the lower electrode, and the negatively charged black particles move upward and close to the upper electrode. Therefore, a black picture may be observed from the top.
An electronic display device applicable to colorful display is also disclosed in the prior art, in order to alleviate the problem of the single-color (monochromic) display.
For example, Chinese patent application publication No. 103576404A discloses an electronic ink paper capable of displaying a black/white pattern and a colorful pattern. This electronic ink paper may include an electronic ink paper having its upper-layer transparent, a transparent layer, a transparent pixel electrode, microcapsules having their upper-layers transparent, a first positively charged colorful dye, a first negatively charged colorful dye, transparent liquid, a vertically transparent electrode, an electronic ink paper having its lower-layer transparent, a colorful substrate, microcapsules having their lower-layers transparent, a second positively charged colorful dye, and a second negatively charged colorful dye. The electronic ink paper may generate a black/white pattern and a colorful pattern. Although the above-mentioned technical solution may display a colorful pattern, the dying on the charged particles by using the dye is unstable, and has the disadvantages of the colorful development being not enough even and the color being not fresh. Therefore, it is desirable to provide an improved colorful electronic display device.